The invention concerns the installation of large bridge sections, or even the entire pre-completed bridge, on a pier or piers at a high level above the water.
Hitherto, such bridges had to be built in manageable small sections and hoisted piece-by-piece by cranes from a supply barge or barges floating below the bridge. An alternative method was to install a new span by launching it from a completed span, if the new span was not too large.
Heretofore, hoisting the whole bridge or a complete span from outside the piers has been avoided because of problems caused by hoisting the bridge or complete span eccentrically from one side and by having to move the bridge or span laterally to the central position on the pier on a higher level.
An object of the invention is to enable a bridge to be positioned longitudinally in the central position through a slot provided in the bridge pier, and then to be moved laterally to a position in the center of the pier at low level. Then the pier is hoisted up by jacks placed directly over the top of the pier.